reCaptcha stopped working

[mastum]

Description

No errors in logs, keys are valid, no changes have been made to code or settings. It just fails with "invalid captcha value" when clicking submit now, even with a green checkbox.

More info: https://www.simplemachines.org/community/index.php?topic=572333.0

Steps to reproduce

1. Activate reCaptcha v2 antispam
2. Try to register a new user

Environment (complete as necessary)

• Version/Git revision: 6103f58
• Database Type: MariaDB
• Database Version: 10.1.44
• PHP Version: 7.3.6

[dhmyrdal]

This happened suddenly with no change on our servers, about March 17h might be some change on Google's side? Google admin console indicate that a "normal" 50% of attempts are rejected.

Long term SMF could support reCaptcha v.3 ?